The present invention relates to high speed data transfer between electronic devices. More specifically, the present invention relates to an application processor circuit compliant with MMC/SD/SDIO protocol, and to a portable electronic device including the application processor circuit.
The application processors in more and more portable electronic devices, e.g., personal digital assistance (PDA), portable music player and notebook computer, support interfaces compliant with MMC/SD/SDIO protocol, since these interfaces can achieve high efficiency in data transfer and are easy to use. The PDA devices, for example, implement some functions by means of external cards connected via an SD card slot to provide a variety of choices to the user and enable the user to configure the PDA device. These functions not only include expansion of the memory capacity of the PDA device, but also include other PDA functions that support connections with various other peripheral devices. Specifically, for example, SD (Secure Digital) memory card is widely used to expand the memory capacity of the PDA devices. The increasingly popular SDIO (Secure Digital Input/Output) card is based on the SD memory card, and is compatible therewith in terms of electrical and mechanical configuration. The common functions of SDIO card include Bluetooth adapter, WLAN adaptor, GPS receives, and so on. In addition, the SDIO specification has introduced the concept of “SDCombo”, which refers to a combination of both SD memory card and SDIO card functions. The SD card slot of existing PDA devices can support the SD memory card and SDIO card, and can also support MMC (Multimedia Card), and the MMC protocol is an earlier developed memory card specification than the SD specification. Incidentally, in the context of the present application, concepts such as “SD protocol”, “SD interface” and the like are used in many cases to represent the MMC/SD/SDIO protocol, so as to make the description more concise.
Existing application processor chips supporting the SD interface only include SD host logic to support SD slave device, but cannot achieve interconnection therebetween via such interfaces. For example, the existing PDA devices with SD slots only have SD host logic to support SD slave devices such as MMC card, SD memory card, SDIO card and SDCombo card. However, two PDA devices cannot enable data exchange therebetween though the SD interface. The existing data transfer compliant with SD protocol can only be done between a host and a slave device, but in practical use, it may be desirable to conduct data transfer between any two devices which support SD protocol, e.g., between two chips within the same package, or between two PDA devices which exchange data therebetween. Thus, there exists a need that an electronic device incorporating application processor chip, e.g., PDA, can serve both as a SD host and as a SD slave device, so as to provide more convenience in the data transfer.
U.S. Patent Application No. 2005/0197017A1 uses SD protocol, but the application relates to a new protocol which, based on the SD protocol, inquires about the conventional protocols that the apparatus supports. However, the apparatus itself still serves as a host controller, and is irrelevant to the slave device.